IRIS 2 Loses KARA's Kang Ji Young

Ji Young, a member of ultra-girly K-POP Idol group KARA, was supposed to play an NSS agent in the upcoming drama IRIS 2, but she suddenly dropped out. Supposedly there were contractual issues, so now the production has to find someone to replace her, and who knows if this will cause a delay in filming depending on how important of a role this character plays in the drama.
Who do you think would make a good replacement?
KrisE! @K_Kisses_KrisE